I control can be instantiated than you can use following code

IF TYPE([CREATEOBJECT("PDF.Pdfctrl.5")]) = "O"
  * Control is installed an registered 
ELSE
ENDIF

Otherwise you'll have to check the registry for the presence of the specific key.

>What I wonder... Such a registration might be done in the initcode. But can it be called more often? Or.. is there a lowlevel way to find out whether the control has already been registered?